Preheat oven to 375 degrees.
In a large cast-iron skillet fry bacon, once cooked chop. Reserve bacon grease.
Add butter to the cast-iron skillet containing bacon grease, heat and melt.
Add cleaned and halved Brussel sprouts and minced shallots to the cast-iron skillet. Season with salt, pepper, and saute for 10-15 minutes. Stirring occasionally. (Note: I prefer to carmelize the sprouts and shallots. I will cook in small batches until all sprouts have been prepared and then add all back into the skillet to re-heat).
Remove from heat and slowly drizzle with heavy cream and top with the cheeses and bacon bits. Bake until cheese is bubbly, about 10-15 minutes.
The cheese should become a soft golden color. If not, place the cast-iron skillet under the broiler until desired golden color is acheived.
Remove, serve and enjoy!
To reheat any leftovers add a small amount of cream, top with cheese, and bake until heated and the cheese has melted and become bubbly.